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                <title>Identification - Formula prediction - Elemental heuristics</title>
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                <h1>Formula prediction - Elemental heuristics</h1>

                <h2>Description</h2>

                <p>
					This heuristics checks the formula's element counts as defined in Kind and Fiehn, BMC Bioinformatics 2007 (doi:10.1186/1471-2105-8-105).
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                <h4>Method parameters</h4>
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                        <dt>H/C ratio</dt>
                        <dd>0.1 &lt;= H/C ratio &lt;= 6</dd>

                        <dt>NOPS/C ratios</dt>
                        <dd>N/C ratio &lt;= 4, O/C ratio &lt;= 3, P/C ratio &lt;= 2, S/C ratio &lt;= 3</dd>

                        <dt>Multiple element counts</dt>
                        <dd>
                            if NOPS all &gt; 1 then N&lt; 10, O &lt; 20, P &lt; 4, S &lt; 3<br>
                            if NOP all &gt; 3 then N &lt; 11, O &lt; 22, P &lt; 6<br>
                            if OPS all &gt; 1 then O &lt; 14, P &lt; 3, S &lt; 3<br>
                            if PSN all &gt; 1 then P &lt; 3, S &lt; 3, N &lt; 4<br>
                            if NOS all &gt; 6 then N &lt; 19 O &lt; 14 S &lt; 8                        
                        </dd>

                                                
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